Epoxy resin curing agents, epoxy resin compositions, paints and adhesives

Abstract

Provided are: an epoxy resin curing agent including an amine composition or a modified product thereof, the amine composition containing m-xylylenediamine and p-xylylenediamine at a mass ratio of 99 / 1 to 51 / 49; an epoxy resin composition; and a paint and an adhesive each containing the epoxy resin curing agent and the epoxy resin composition.

Description

[Technical Field]

[0001] The present invention relates to an epoxy resin curing agent, an epoxy resin composition, a coating material, and an adhesive. [Background technology]

[0002] Xylylenediamine is a useful compound as a raw material for polyamide resins, epoxy resin curing agents, isocyanate compounds, etc. However, xylylenediamine is known to be susceptible to deterioration due to light, heat, oxygen, etc., and to cause deterioration such as coloration and odor during storage. Therefore, for example, Patent Document 1 discloses a xylylenediamine having excellent storage stability and not suffering from quality deterioration such as coloration even when stored for a long period of time. The xylylenediamine is a container-packed solid xylylenediamine that is prepared by filling a container with liquid xylylenediamine having a hue of 20 or less as APHA and then solidifying it in the container, and that is stored in the solid state and then melted and measured as a liquid, and has a hue of 20 or less as APHA.

[0003] Furthermore, polyamide resins using xylylenediamine as the main diamine component are useful as molding materials containing glass fibers or inorganic fillers because they have excellent mechanical properties such as strength and elastic modulus. Patent Document 2 discloses a xylylenediamine composition containing xylylenediamine and a predetermined amount of bis(methylbenzyl)amine, and a method for producing a polyamide resin using the composition, and describes that the polyamide resin is suitable for use as a material for packaging films, hollow containers, various molding materials, fibers, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-154426 [Patent Document 2] International Publication No. 2014 / 178270 Summary of the Invention [Problem to be solved by the invention]

[0005] Epoxy resin compositions using various polyamines such as xylylenediamine as epoxy resin curing agents are widely used in the fields of coatings such as anticorrosion coatings for ships, bridges, and iron structures on land and at sea, as well as in the fields of civil engineering and construction such as linings, reinforcing and repair materials for concrete structures, flooring materials for buildings, linings for water supply and sewerage systems, paving materials, adhesives, etc. Among these, polyamines for paints or adhesives differ from polyamines used as raw materials for polyamide resins in that it is important that the resulting paints or adhesives have good water resistance, coating film appearance, coating film physical properties, etc. However, Patent Documents 1 and 2 do not consider the performance when xylylenediamine is used as an epoxy resin curing agent for paints or adhesives, and there is still room for improvement in water resistance, etc.

[0006] An object of the present invention is to provide an epoxy resin curing agent and an epoxy resin composition which can give a coating material or adhesive having excellent water resistance, as well as a coating material and an adhesive containing the same. [Means for solving the problem]

[0007] The present inventors have found that the above-mentioned problems can be solved by an epoxy resin curing agent containing an amine composition containing metaxylylenediamine and paraxylylenediamine in a predetermined mass ratio or a modified product thereof. That is, the present invention relates to the following. [1] An epoxy resin curing agent comprising an amine composition containing metaxylylenediamine and paraxylylenediamine in a mass ratio of 99 / 1 to 51 / 49, or a modified product thereof. [2] The epoxy resin curing agent according to the above [1], wherein the mass ratio of metaxylylenediamine to paraxylylenediamine in the amine composition is 99 / 1 to 71 / 29. [3] The epoxy resin curing agent according to the above [1] or [2], wherein the mass ratio of metaxylylenediamine to paraxylylenediamine in the amine composition is 85 / 15 to 75 / 25. [4] The amine composition according to any one of the above [1] to [3], wherein the total content of metaxylylenediamine and paraxylylenediamine in the amine composition is 50% by mass or more. [5] The epoxy resin curing agent according to any one of the above [1] to [4], wherein the modified amine composition is a reaction product of the amine composition and an epoxy compound having at least one epoxy group. [6] An epoxy resin composition containing an epoxy resin and the epoxy resin curing agent according to any one of the above [1] to [5]. [7] A paint containing the epoxy resin composition described in [6] above. [8] An adhesive containing the epoxy resin composition described in [6] above. [Effects of the Invention]

[0008] The epoxy resin curing agent and epoxy resin composition of the present invention can provide a coating material or adhesive having excellent water resistance. The epoxy resin composition of the present invention is suitable for use in various coating materials such as marine coating materials, heavy-duty anticorrosion coating materials, tank coating materials, pipe interior coating materials, exterior coating materials, and floor coating materials, as well as various adhesive materials for the civil engineering and construction fields and the film field. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a graph showing the relationship between the mass ratio of metaxylylenediamine and paraxylylenediamine and the freezing point in an amine composition comprising the two. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Epoxy resin hardener] The epoxy resin curing agent of the present invention comprises an amine composition containing metaxylylenediamine and paraxylylenediamine in a mass ratio of 99 / 1 to 51 / 49, or a modified product thereof. By using the above-mentioned epoxy resin curing agent, it is possible to provide a coating material or adhesive having excellent water resistance. Hereinafter, the epoxy resin curing agent of the present invention may also be simply referred to as "the curing agent of the present invention."

[0011] It is not clear why use of the curing agent of the present invention allows for the production of coatings or adhesives with excellent water resistance, but it is thought that by mixing metaxylylenediamine and paraxylylenediamine in an appropriate compounding ratio, the three-dimensional crosslinked structure of the cured product of the obtained epoxy resin composition changes, resulting in improved water resistance compared to when metaxylylenediamine or paraxylylenediamine is used alone.

[0012] Furthermore, because paraxylylenediamine has a high freezing point, there is room for improvement in workability and storage stability under low-temperature conditions. However, amine compositions in which the mass ratio of metaxylylenediamine to paraxylylenediamine falls within the range specified in the present invention have a low freezing point. In particular, amine compositions in which the mass ratio of metaxylylenediamine to paraxylylenediamine falls within the ranges of 85 / 15 to 75 / 25, or even 85 / 15 to 77 / 23, or 83 / 17 to 77 / 23, have a lower freezing point than metaxylylenediamine alone. Therefore, when the curing agent of the present invention containing the amine composition or a modified product thereof is used, not only is water resistance improved, but the composition is less likely to solidify under low-temperature conditions, and workability under low-temperature conditions is further improved.

[0013] The mass ratio of meta-xylylenediamine to para-xylylenediamine (meta-xylylenediamine / para-xylylenediamine) in the amine composition used in the present invention is 99 / 1 to 51 / 49, preferably 99 / 1 to 71 / 29, from the viewpoint of obtaining a coating material or adhesive having excellent water resistance. Furthermore, from the viewpoint of obtaining a coating material or adhesive having excellent water resistance and improving workability under low temperature conditions, it is more preferably 85 / 15 to 75 / 25, even more preferably 85 / 15 to 77 / 23, and still more preferably 83 / 17 to 77 / 23.

[0014] From the viewpoint of obtaining a coating material or adhesive having excellent water resistance, the total content of meta-xylylenediamine and para-xylylenediamine in the amine composition is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and may be 100% by mass.

[0015] The method for preparing the amine composition is not particularly limited, and can be, for example, by blending and mixing predetermined amounts of meta-xylylenediamine and para-xylylenediamine. Alternatively, if it is possible to adjust the catalyst used and production conditions to perform reactions in parallel to produce meta-xylylenediamine and para-xylylenediamine in a predetermined ratio, such a method can also be used. In this case, the contents and ratios of meta-xylylenediamine and para-xylylenediamine in the amine composition can be determined by gas chromatography analysis or the like.

[0016] Specific examples of modified amine compositions contained in the curing agent of the present invention include reaction products obtained by reacting the amine composition with an epoxy compound having at least one epoxy group, an unsaturated hydrocarbon compound, a carboxylic acid or a derivative thereof, etc.; and Mannich reaction products obtained by reacting the amine composition with a phenol compound and an aldehyde compound. Among these, from the viewpoint of obtaining a coating material or adhesive having excellent water resistance, the modified amine composition is preferably a reaction product of the amine composition with an epoxy compound having at least one epoxy group. Hereinafter, this reaction product may also be simply referred to as "the reaction product."

[0017] The epoxy compound used in the reaction product of the amine composition and an epoxy compound having at least one epoxy group may be a compound having at least one epoxy group, and a compound having two or more epoxy groups is more preferred. Specific examples of epoxy compounds include epichlorohydrin, butyl diglycidyl ether, neopentyl glycol diglycidyl ether, 1,3-propanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, biphenol diglycidyl ether, dihydroxynaphthalene diglycidyl ether, dihydroxyanthracene diglycidyl ether, triglycidyl isocyanurate, tetraglycidyl glycoluril, multifunctional epoxy resins having a glycidylamino group derived from metaxylylenediamine, and glycidylamino groups derived from 1,3-bis(aminomethyl)cyclohexane. Examples of the epoxy resin include polyfunctional epoxy resins having a glycidylamino group derived from diaminodiphenylmethane, polyfunctional epoxy resins having a glycidylamino group derived from paraaminophenol, polyfunctional epoxy resins having a glycidyloxy group derived from paraaminophenol, polyfunctional epoxy resins having a glycidyloxy group derived from bisphenol A, polyfunctional epoxy resins having a glycidyloxy group derived from bisphenol F, polyfunctional epoxy resins having a glycidyloxy group derived from phenol novolac, and polyfunctional epoxy resins having two or more glycidyloxy groups derived from resorcinol. These may be used alone or in combination of two or more. From the viewpoint of forming an epoxy resin cured product having excellent water resistance and from the viewpoint of curability, the epoxy compound is more preferably a compound containing an aromatic ring or an alicyclic structure in the molecule, even more preferably a compound containing an aromatic ring in the molecule, and even more preferably a polyfunctional epoxy resin having a glycidyloxy group derived from bisphenol A.

[0018] The reaction product can be obtained by subjecting an amine composition and an epoxy compound to a ring-opening addition reaction using a known method. For example, the amine composition can be charged into a reactor, and the epoxy compound can be added all at once or in portions, such as by dropwise addition, followed by heating and reaction. The addition reaction is preferably carried out under an inert atmosphere such as nitrogen gas.

[0019] The amounts of the amine composition and the epoxy compound used are not particularly limited as long as the ratio is such that the resulting reaction product contains an amino group having active hydrogen, but from the viewpoint of the resulting reaction product exhibiting its function as an epoxy resin curing agent, it is preferable to use an excess amount of the amine composition relative to the epoxy equivalent of the epoxy compound in the addition reaction. Specifically, the amine composition and the epoxy compound are used so that the ratio of the number of active hydrogens in the amine composition to the number of epoxy groups in the epoxy compound (number of active hydrogens in the amine composition / number of epoxy groups in the epoxy compound) is preferably 50 / 1 to 4 / 1, more preferably 20 / 1 to 8 / 1.

[0020] The temperature and reaction time during the addition reaction can be selected as appropriate, but from the viewpoints of reaction rate, productivity, and prevention of decomposition of raw materials, the temperature during the addition reaction is preferably 50 to 150° C., more preferably 70 to 120° C. The reaction time is preferably 0.5 to 12 hours, more preferably 1 to 6 hours, after completion of addition of the epoxy compound.

[0021] The curing agent of the present invention may be a curing agent comprising the amine composition or a modified product thereof, or may contain other curing agent components. The curing agent component means a component contained in the curing agent and having two or more functional groups capable of reacting with epoxy groups in the epoxy resin, and examples of other curing agent components include polyamine compounds other than the amine composition and its modified products. However, from the viewpoint of obtaining a coating material or adhesive having excellent water resistance, the content of the amine composition and its modified product in the curing agent of the present invention is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and may be 100% by mass, based on the total curing agent components in the curing agent.

[0022] The curing agent of the present invention may further contain known curing accelerators, non-reactive diluents such as benzyl alcohol, etc., within the range that does not impair the effects of the present invention.

[0023] When the curing agent of the present invention contains a modified amine composition, the active hydrogen equivalent of the curing agent is preferably 85 or more, more preferably 90 or more, from the viewpoint of obtaining a coating material or adhesive having excellent water resistance, and is preferably 120 or less, more preferably 110 or less, from the viewpoint of improving curability. The active hydrogen equivalent weight (hereinafter also referred to as "AHEW") is the mass of an epoxy resin curing agent per mole of active hydrogen. When the curing agent of the present invention uses the non-reactive diluent, it is preferable that the AHEW of the total amount of the curing agent solution including the diluent falls within the above range.

[0024] [Epoxy resin composition] The epoxy resin composition of the present invention contains an epoxy resin and the epoxy resin curing agent. The epoxy resin composition of the present invention has high water resistance and is suitable for use in paints or adhesives.

[0025] <Epoxy resin> The epoxy resin, which is the main component of the epoxy resin composition, may be any of a saturated or unsaturated aliphatic compound, alicyclic compound, aromatic compound, and heterocyclic compound. From the viewpoint of obtaining a cured product with high water resistance, an epoxy resin containing an aromatic ring or alicyclic structure in the molecule is preferred. Specific examples of the epoxy resin include at least one resin selected from the group consisting of epoxy resins having glycidylamino groups derived from meta-xylylenediamine, epoxy resins having glycidylamino groups derived from para-xylylenediamine, epoxy resins having glycidylamino groups derived from 1,3-bis(aminomethyl)cyclohexane, epoxy resins having glycidylamino groups derived from 1,4-bis(aminomethyl)cyclohexane, epoxy resins having glycidylamino groups derived from diaminodiphenylmethane, epoxy resins having glycidylamino groups and / or glycidyloxy groups derived from para-aminophenol, epoxy resins having glycidyloxy groups derived from bisphenol A, epoxy resins having glycidyloxy groups derived from bisphenol F, epoxy resins having glycidyloxy groups derived from phenol novolac, and epoxy resins having glycidyloxy groups derived from resorcinol. Two or more of the above epoxy resins can also be used in combination.

[0026] Among the above, from the viewpoint of obtaining a cured product with high water resistance, the epoxy resin is preferably one having as its main component at least one selected from the group consisting of epoxy resins having a glycidylamino group derived from meta-xylylenediamine, epoxy resins having a glycidylamino group derived from para-xylylenediamine, epoxy resins having a glycidyloxy group derived from bisphenol A, and epoxy resins having a glycidyloxy group derived from bisphenol F, and from the viewpoint of obtaining a cured product with high water resistance, availability, and economy, one having as its main component an epoxy resin having a glycidyloxy group derived from bisphenol A is more preferred. The term "main component" as used herein means that other components may be contained within the scope of the present invention, and preferably means 50 to 100% by mass of the total, more preferably 70 to 100% by mass, and even more preferably 90 to 100% by mass.

[0027] The content of the epoxy resin curing agent in the epoxy resin composition of the present invention is an amount such that the ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the epoxy resin (number of active hydrogens in the epoxy resin curing agent / number of epoxy groups in the epoxy resin) is preferably 1 / 0.5 to 1 / 2, more preferably 1 / 0.75 to 1 / 1.5, and even more preferably 1 / 0.8 to 1 / 1.2.

[0028] The epoxy resin composition of the present invention may further contain other components such as modifying components such as fillers and plasticizers, flow-adjusting components such as thixotropic agents, pigments, leveling agents, tackifiers, and elastomer fine particles, depending on the intended use. However, from the viewpoint of effectively obtaining the effects of the present invention, the total amount of the epoxy resin and the epoxy resin curing agent in the epoxy resin composition is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and may be 100% by mass.

[0029] The epoxy resin composition of the present invention can be prepared by mixing an epoxy resin, an epoxy resin curing agent, and other components as required using known methods and equipment. The order of mixing the components contained in the epoxy resin composition is also not particularly limited. The epoxy resin curing agent may be prepared and then mixed with the epoxy resin, or the epoxy resin may be prepared by simultaneously mixing the components constituting the epoxy resin curing agent and other components with the epoxy resin.

[0030] [Paints, adhesives] The present invention provides a coating material and an adhesive containing the epoxy resin composition. The coating material and adhesive of the present invention have high water resistance due to the inclusion of the epoxy resin composition. The coating material and adhesive containing the epoxy resin composition of the present invention have a low freezing point due to the inclusion of the epoxy resin curing agent of the present invention, and therefore can be made into a coating material and adhesive that are highly workable under low temperature conditions and highly water-resistant.

[0031] From the viewpoint of improving water resistance, the content of the epoxy resin composition in the coating material or adhesive is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, and may be 100% by mass.

[0032] Examples of the paints include marine paints, heavy-duty anticorrosion paints, tank paints, paints for pipe interiors, paints for exteriors, paints for flooring, etc. Examples of the adhesives include various adhesives for use in the fields of civil engineering and construction and film. [Example]

[0033] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. Various measurements and evaluations in each example were carried out as follows.

[0034] (Dry to the touch) A zinc phosphate-treated iron plate (SPCC-SD PB-N144, manufactured by Paltec Co., Ltd., 0.8 × 70 × 150 mm) was used as the substrate. The epoxy resin composition of each example was applied to the substrate using an applicator at 23°C and 50% RH to form a coating film (coating film thickness immediately after application: 200 μm). This coating film was stored at 23°C and 50% RH, and after one day, it was evaluated by touch using the following criteria. The results are shown in Table 1. Ex: Excellent (the coating does not become sticky even when pressed with a thumb with a force of approximately 50N, and no fingerprints remain) G: Good (the coating is not sticky when pressed with a thumb with a force of about 50 N, but fingerprints remain after touching) F: Fair (the coating is sticky when pressed with a thumb with a force of about 50 N) P: Poor (the coating is sticky when pressed with a thumb with a force of about 5N)

[0035] (Pencil hardness) The epoxy resin composition was applied to a substrate (zinc phosphate-treated iron plate) in the same manner as above to form a coating film (thickness immediately after application: 200 μm). This coating film was stored under conditions of 23°C and 50% RH, and after 1, 2, and 7 days, the pencil hardness was measured in accordance with JIS K5600-5-4:1999. The results are shown in Table 1.

[0036] (Water resistance spot test) The epoxy resin composition was applied to a substrate (zinc phosphate-treated iron plate) in the same manner as above to form a coating film (thickness immediately after application: 200 μm). This coating film was stored under conditions of 23°C and 50% RH, and after 1, 2, and 7 days, 2 to 3 drops of pure water were applied to the coating surface using a dropper, and the area was then capped with a 50 mL screw cap bottle. After 24 hours, the water was wiped off, and the appearance was visually observed and evaluated according to the following criteria. The results are shown in Table 1. Ex: No change G: Slight changes, but good F: Change

[0037] (RCI curing speed) Each epoxy resin composition was applied to a glass plate (25 x 348 x 2.0 mm, manufactured by Taiyu Kizai Co., Ltd.) at 23°C and 50% RH using a 76 μm applicator to form a coating. The glass plate with the coating was then placed in a paint drying time measuring device (manufactured by Taiyu Kizai Co., Ltd.), and the time required to reach each drying stage (touch-dry, semi-dry, completely dry) was measured according to the following criteria. The results are shown in Table 1. A shorter time indicates a faster curing rate. Set to Touch: The time it takes for the needle to start leaving a mark on the glass plate Semi-dry (Dust Free): The time it takes for the needle marks to appear on the surface of the paint film. Dry through: The time when no trace of the needle remains on the coating

[0038] (Appearance of the coating) The epoxy resin composition was applied to a substrate (a zinc phosphate-treated iron plate) in the same manner as above to form a coating film (thickness immediately after application: 200 μm). The appearance of the resulting coating film was visually observed after one day, and the transparency, smoothness, and gloss were evaluated according to the following criteria. <Transparency> Ex: No turbidity G: Slightly cloudy, but no problem for use F: Cloudy <Smoothness> Ex: No unevenness G: There are slight irregularities, but this does not affect use. F: Uneven <Glossiness> Ex: Glossy G: Slightly less glossy, but still usable F: Matte

[0039] Example 1 (Preparation and Evaluation of Epoxy Resin Curing Agent and Epoxy Resin Composition (Paint)) Preparation of Amine Composition Metaxylylenediamine (MXDA, manufactured by Mitsubishi Gas Chemical Co., Inc.) and paraxylylenediamine (PXDA, manufactured by Mitsubishi Gas Chemical Co., Inc.) were blended and mixed in a mass ratio of 90 / 10 to prepare an amine composition.

[0040] [Preparation of epoxy resin curing agent] A 1-liter separable flask equipped with a stirrer, thermometer, nitrogen inlet tube, dropping funnel, and condenser was charged with 340 g of the amine composition and heated to 80°C while stirring under a nitrogen stream. While maintaining the temperature at 80°C, 186 g (an amount such that the number of active hydrogens in the amine composition / the number of epoxy groups in the epoxy compound = 10 / 1) of a multifunctional epoxy resin ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 186 g / equivalent) derived from bisphenol A was added dropwise over 2 hours. After the addition was completed, the temperature was raised to 100°C and the reaction was continued for 2 hours, yielding a reaction product of the amine composition and jER828. The reaction product was diluted with benzyl alcohol, a non-reactive diluent, in an amount equivalent to 40% by mass of the total amount, yielding an epoxy resin curing agent with a concentration of the reaction product of 60% by mass. The active hydrogen equivalent weight (AHEW) of the epoxy resin curing agent (total amount including benzyl alcohol) was 97.4.

[0041] [Preparation of epoxy resin composition (paint)] A polyfunctional epoxy resin having glycidyloxy groups derived from bisphenol A ("jER828" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 186 g / equivalent) was used as the epoxy resin, which was the main component of the epoxy resin composition. The epoxy resin and the epoxy resin curing agent were mixed together so that the ratio of the number of active hydrogens in the epoxy resin curing agent to the number of epoxy groups in the main epoxy resin (number of active hydrogens in epoxy resin curing agent / number of epoxy groups in main epoxy resin) was 1 / 1, thereby preparing an epoxy resin composition (paint). The obtained epoxy resin composition was subjected to various evaluations using the methods described above, and the results are shown in Table 1.

[0042] Examples 2 to 6, Comparative Examples 1 to 3 An amine composition was prepared by blending metaxylylenediamine and paraxylylenediamine in the mass ratio shown in Table 1. Using this amine composition, an epoxy resin curing agent and an epoxy resin composition were prepared in the same manner as in Example 1, and various evaluations were carried out. The results are shown in Table 1.

[0043] [Table 1]

[0044] From Table 1, it can be seen that the epoxy resin compositions containing the epoxy resin curing agent of the present invention have superior water resistance to the epoxy resin compositions of Comparative Examples 1 to 3. In addition, the curing speed and coating film performance such as hardness and appearance of the coating film are at levels that do not pose any problems in practical use.

[0045] Fig. 1 is a graph showing the relationship between the mass ratio of meta-xylylenediamine and para-xylylenediamine and the freezing point of an amine composition comprising the two. As shown in Fig. 1, when the mass ratio of meta-xylylenediamine to para-xylylenediamine (meta-xylylenediamine / para-xylylenediamine) is around 80 / 20, the freezing point is lower than when meta-xylylenediamine alone or para-xylylenediamine alone is used. The freezing point of the amine composition was measured by the following method.

[0046] [Freezing point measurement] Measurements were carried out in accordance with JIS K0065-1992 "Method for measuring the freezing point of chemical products." The sample was placed in the test tube up to the marked line, and a silicone stopper with a thermometer and a stirring rod inserted was attached. A large test tube was then attached as a jacket to cover the test tube. This was placed in a bathtub containing a cryogen and cooled while stirring. Ice water / sodium chloride or water cooled with Coolnix was used as the cryogen. The thermometer reading began to rise as the sample began to solidify, and the temperature at which it became constant was taken as the freezing point. If the temperature did not become constant and the reading began to fall, the point obtained by extrapolating a straight line from the cooling curve immediately after the maximum reading was taken as the freezing point. Measurements were performed three times, and the average was calculated. [Industrial Applicability]

[0047] The epoxy resin curing agent and epoxy resin composition of the present invention can provide a coating material or adhesive having excellent water resistance. The epoxy resin composition of the present invention is suitable for use in various coating materials such as marine coating materials, heavy-duty anticorrosion coating materials, tank coating materials, pipe interior coating materials, exterior coating materials, and floor coating materials, as well as various adhesive materials for the civil engineering and construction fields and the film field.

Claims

1. An epoxy resin curing agent comprising a modified amine composition containing metaxylylenediamine and paraxylylenediamine in a mass ratio of 99 / 1 to 51 / 49, The epoxy resin curing agent, wherein the modified amine composition comprises a reaction product of the amine composition and an epoxy compound having at least one epoxy group.

2. 2. The epoxy resin curing agent according to claim 1, wherein the mass ratio of metaxylylenediamine to paraxylylenediamine in the amine composition is 99 / 1 to 71 / 29.

3. 3. The epoxy resin curing agent according to claim 1, wherein the mass ratio of metaxylylenediamine to paraxylylenediamine in the amine composition is 85 / 15 to 75 / 25.

4. An epoxy resin curing agent according to any one of claims 1 to 3, wherein the mass ratio of metaxylylenediamine to paraxylylenediamine in the amine composition is 83 / 17 to 77 / 23.

5. 5. The epoxy resin curing agent according to claim 1, wherein the total content of metaxylylenediamine and paraxylylenediamine in the amine composition is 50 mass% or more.

6. An epoxy resin curing agent described in any one of claims 1 to 5, wherein the epoxy compound contains an aromatic ring or an alicyclic structure in the molecule.

7. The epoxy resin curing agent according to any one of claims 1 to 6, wherein the reaction product is obtained by using the amine composition so that the ratio of the number of active hydrogens in the amine composition to the number of epoxy groups in the epoxy compound (number of active hydrogens in the amine composition / number of epoxy groups in the epoxy compound) is 50 / 1 to 4 / 1, and carrying out a ring-opening addition reaction.

8. An epoxy resin composition comprising an epoxy resin and the epoxy resin curing agent according to any one of claims 1 to 7.

9. A paint containing the epoxy resin composition according to claim 8.

10. An adhesive comprising the epoxy resin composition according to claim 8.

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